The present invention relates to phase modulation and motion sensing devices and more particularly to a method and apparatus for performing all-optical, self-aligning, holographic phase modulation and motion sensing utilizing a zero external electric field photorefractive effect in paraelectric materials. 2. Description Of The Prior Art
Modernly, a wide variety of sensing devices, including electrical, mechanical and optical sensors, as well as various combinations of such sensors, are utilized in a large number of applications, including manufacturing and testing, research and development, information processing, communications, consumer products, and military applications, to name just a few. Various advantages and disadvantages, relating to a host of factors, including size, sensitivity, stability, responsiveness, alignment difficulty and cost, to name just a few, are attendant upon different types of sensors and are of critical concern depending upon the particular application or need to which a sensor is to be addressed. To this end, sensor technology is a rapidly growing field with great attention being paid to new and innovative types of sensors and sensing methods. In particular, all-optical sensors and sensing methods are presently receiving considerable attention for use in applications where electrical signals cannot be used or are impractical. Such applications include, but are not limited to, aqueous, explosive, corrosive and electromagnetically sensitive environments.
With respect to all-optical sensors, intensity modulating sensors, primarily because of their relative ease of alignment, have traditionally been preferred over interferometric and phase modulation techniques. However, even intensity modulating all-optical sensors have significant alignment problems, typically due to the precise component positioning required to obtain good sensor sensitivity. These alignment problems also result in sensors that are not mechanically robust.
Thus, a need exists for an all-optical sensor and sensing method that may be used in applications where electrical signals are forbidden or are impractical, that is relatively mechanically robust, that provides ease of alignment and that operates via a phase modulation, rather than an intensity modulation, technique.